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IMPs

#1 User is offline   hallway 

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Posted 2003-February-28, 12:19

The section header is "Beginner"  so to any responses please apply the KISS principal (keep it simple sweetie  :)

At my hometown bridge club all scoring is Match Points - I have asked but no one has been able to give me an understanding of the International Match Points scoring that seems to be the method of choice on BBO.

On BBO:

We bid 4S and made 7 -  the Opps were rewarded with + 9.6 imps

They bid 4S and made 7  - and we were rewarded with + 10.5 imps

I've no quarrel with receiving the extra 0.9  ;D  - just curious to know why we deserved it  ?

Another thing that puzzled me  :-[  at the conclusion of one hand that I thought we did ok with I watched the Imp counter (top left)  and was pleased to see us go into the positive - progress at last  :D   Alas it didn't last  :(  half way through playing the next hand a movement caught my eye and woe was me the Imps counter changed and that lovely + sign changed to a minus  !!      :o  it might have waited till I'd finished playing the hand   :'(

So many posts speak of a different approach to one's bidding depending on which scoring method is in use at the time   -  keeping it simple now  :) -  what are the fundamental differences ?

Thanks in anticipation
Maureen

Anyone who stops learning is old whether they be twenty or eighty. Anyone who keeps learning stays young (Henry Ford)      -    here's hoping  M
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Posted 2003-February-28, 12:53

Hi,

Imps is one way to compare duplicate results.

You could play total points. You play the hand, and get say 620, at the "other" table they are down one for -100 so your ntet score (total points) is 720. But there are some really wild swings, so one bad hand (say you bid 7H and they set it with a ruff at trick one while 7NT bid at the other table, would lead to such a large total point lead that, well, you lose pretty much regardless how well you play the rest of the hands.

Rather than allow one hand or two key hands decide everything, the wide range of total point scores has been replace by a table. You look up the difference in the table and see how many imps you get. Part of the table is:
Points     IMPs
20-40      1
50-80      2
90-120    3
130-160    4
170-210    5
220-260    6
270-310    7
320-360    8
370-420    9
430-490    10
500-590    11
600-740    12
750-890    13
900-1090    14
1100-1290    15
1300-1490   16
1500-1740   17
1750-1990   18
2000-2240   19
2250-2490   20
2500-2990   21
3000-3490   22
3500-3990   23
4000+           24

The way the scoring works, if you are +10 imps on a hnad, your opponents are -10 imps.  At the BBO, your imps are figured against each other table... and then averaged.

For instance if you are +100  and two other pairs with your hand are +!00 and -200. What is your imp score?

Your 100 versus the other 100 is a tie, for 0 imps
Your +100 verus -200 for the other guys with your cards is a +300 for you. Looking in the table, you see that +300 is +7 imps for you.  So +0 +7 imps total 7imps/2 comparisons, your average score is +3.5 imps.

Hope that helps.
--Ben--

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Posted 2003-March-01, 09:08

THANK YOU  Ben that certainly does help.   8)

I have printed it out and will distribute it to the others I have introduced to BBO

Cheers  M
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Posted 2003-March-01, 11:26

Your welcome.. now i wish I had checked my spelling and other small mistakes.  ;D
--Ben--

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Posted 2003-April-21, 00:47

Hi Maureen,
Will try to present the difference between Matchpoints scoring and IMP scoring and the different strategies on the table depending on scoring method
1. Matchpoints: your result is compared to the results of all the other pairs on the same board and is given some percent between 100 and 0
example: assume 5 tables (10 pairs) and N-S scored different +:
You've scored +140, 3 pairs +110 and only one +100
here you will get 100 % and your opps 0%, at the three tables where +110 scored all N-S and E-W pairs will get 50 %, the last N-Sfor their +100 only will get 0% while there opps E-W for -100 will score 100 %

at the above example there would be no difference whethere you have scored +170, or +420 or +1100

Simply the best result gets 100 % the next gets less.....

2. At IMP's your result is compared to the results of all the other pairs on the same board and is given IMP difference to all other pairs
for example: assume 5 tables (10 pairs) and N-S scored diff rent +:
You've scored +200, 3 pairs +100 and only one passed
here you will get (200-100) = +100 = +3 IMPS (see the table of Ben Inquiry) so you won by 3 imps to every of the three pairs and once (200-0)=+200=+5 imps another five imps from the fitht pair who passed out
IMP scoring is commonly used in teams matches:
for example you''ve made +620 for 4H just, at the other table your team mates sacrificed to 5C for -500 only the difference is +620-500=+120 = +3 IMPS for your team
next board you go down one on 4H for -50, at the other tble opps bid only 3H and made 140, here you get -50 -140 = -190 = -5 IMpS for yoyr team.

the conclusion: when playing IMPS and you have safe way for 9 tricks at 3NT and risky way for +1 (but risking going down) you have to play safe and to get your +400 (or +600 vulnerable) because if trying for +1 and make you will win 1 IMP only but when failed you will loose 10 Imps ( 12 if vulnerable). Opposite when Matchpoints playing for +1 will give appropriate % result more (if all made +1 and only you just made then you will get 0%).
At Matchpoints reasonable risks for making overtricks can be accepted while in IMPS NOT.

Hope above will help you, please do not hesitate to ask if something still unclear.
Best regads, Rado
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Posted 2003-April-21, 12:59

Thank you Rado,

You have affirmed pretty much what we (my little group of BLNs) had decided  -  especially when playing IMPS,  set the contract first.    

Having said that Fred & Wayne advise all BLNs to concentrate on making their contract first and take any overtricks as a bonus. :(

We have recently witnessed (while Kibbing) a couple of hands where the contract seemed safe only to see Declarer seemingly 'lose the plot' and go very light. The ensuing abject apologies showed, though, there had been a purpose - trying for the overtrick .   The result , however, was seeing the IMP counter take a nosedive. :'(
Your advice in action  :o

Cheers
Maureen
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